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For a product to be called "vinegar", it must contain at least $5.0$% acetic acid by mass. A 10.0 g sample of a "raspberry vinegar" is titrated with $0.125 \mathrm{M}$ barium hydroxide and required $37.50 \mathrm{mL}$ for complete neutralization. Can the product be called "vinegar"?

My professor said that the product is vinegar, but I did not understand how he solved it. Could you please tell me what to do? What formulas should I use to solve this kind of problem?

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    $\begingroup$ unless you were given a molecular weight for the raspberry vinegar, I think you'd have to assume that the only species that can react with the barium hydroxide is the acetic acid itself. Therefore you would expect to get barium acetate and water. $\endgroup$ – AngusTheMan Oct 12 '14 at 10:40
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0.125M of $\ce {Ba(OH)2}$ means 0.125 moles of $\ce {Ba(OH)2}$ per volume unit (so far I've only seen liters been used as volume unit) . Assuming that all the $\ce {Ba(OH)2}$ you used was consume on the reaction with the acetic acid, and knowing the ratio of $\ce {Ba(OH)2}$ and acetic acid on the reaction is 1/2 you`d have this reaction:

$$\ce {Ba(OH)2 + 2CH3CO-OH -> Ba(CH3COO)2 + 2H2O}$$

All you need to do is calculate the amount of acetic acid consumed. Knowing the amount of acetic acid consumed based on the amount of moles of $\ce {Ba(OH)2}$ that are present on 37.5mL. Then you need to get the molar mass of acetic acid and calculate the amount of mass of acetic acid you had. Then divide the total mass of vinegar by the mass of acetic acid you found, multiply it by 100 and you'll have the mass percentage of acetic acid.

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